The invention relates to device for installing externally threaded hollow bushes having torsional locking and devices for fitting such bushes.
Such threaded bushes are known in various designs.
In the case of a threaded bush whose external thread itself cuts the corresponding internal thread in the workpiece, the torsional locking is achieved by a radial pinning. With this torsional locking, after screwing in the self-tapping threaded bush, drilling has to be carried out across the junction between the threaded bush and workpiece and a securing pin inserted in the drilled hole. Such an arrangement is very expensive. The threaded bush is expensive in itself, since not only the actual bush body has to be provided but also the securing pin.
Threaded bushes are also known having an external thread in which longitudinal grooves are provided. Wedges are driven into these longitudinal grooves which wedges project beyond the longitudinal grooves and engage in the material of the workpiece. Here also, the fitting of the bushes is very expensive and the threaded bush itself is correspondingly expensive because of its multi-component nature.
In another kind of threaded bush, a toothed securing ring (such as shown in U.S. Pat. No. 2,452,262) is pressed in over the neck of the inserted bush.
The object of the invention is to provide a one-piece threaded bush with torsional locking.